Bicycles delivered prior to 1996, especially mountain bikes, were most often equipped with V-brakes or rim-brakes where a cable actuated cantilever system effectively pinched the wheel rim between two rubber brake pads. Bicycles equipped with such brakes were also equipped with non-disc wheel hubs. Alternatively, bicycle disc-brake systems utilize a frame mounted caliper assembly that squeezes brake pads on a dedicated brake rotor, similar to systems used on modern motorcycles and automobiles. By 2002, the majority of high-end mountain bikes were sold with disc brake systems as standard equipment. Bicycles equipped with such disc-brake systems are equipped with disc-ready wheel hubs, designed specifically to accept the mounting of a dedicated brake rotor. Moving into the future, both rim-brake systems and disc-brake systems will continue to share the market and wheel hub manufacturers will continue to satisfy the needs of both competing systems.
The primary function of a wheel hub is to transfer the load of the vehicle and operator, the stationary part, to the rotating wheel, the moving part, through a wheel bearing assembly. In the case of bicycles, this load transfer is generally accomplished by a single piece wheel hub to which wheel spokes are attached, and within which wheel bearings are housed. Currently manufacturers generally supply two different types of wheels and/or hubs, one being non-disc wheels or hubs (i.e. wheels/hubs not designed to mount a disc brake rotor) and the other being disc wheels or hubs (i.e. wheels/hubs designed to mount a disc brake rotor). Accordingly there is a need for a means for adapting non-disc wheels and hubs to disc wheels and hubs.